1. Field of the Invention
The present invention relates to a method for fabricating a magnetic head, and more particularly to a method for fabricating a magnetic head, wherein magnetic core members of a magnetic head fixed on a turntable of a spin coater are bonded to each other by consistently coating a liquid adhesive at a normal temperature under the state of high speed rotation of the turntable to adhere the core members at the normal temperature, thereby facilitating control of the thickness variation without degrading the magnetic head.
2. Description of the Prior Art
Along with increase of a recording density of a magnetic tape used as a recording medium of a video tape recorder, a magnetic tape having a high residual flux density Br and high coercive force Hc, e.g., a metal magnetic tape which forms a magnetic recording layer by coating metal powders on a non-magnetic body by a binding material, is being widely utilized. When a magnetic head is employed for the metal tape and digital audio tape, the magnetic field intensity of a magnetic gap of the head must be increased owing to the high coercive force of the tapes, which requires a higher saturation magnetic flux density in a magnetic erasing head for erasing signals written on the tape.
Therefore, a head obtained by stacking a ferromagnetic film having a high saturation flux density on a magnetic gap formation plane of a magnetic ferrite block composed of metal oxides is developed via a sputtering, which will be schematically explained hereinbelow.
Referring to FIG. 1 which shows a general magnetic head fabricated by a conventional technique, a magnetic head has a pair of magnetic core members 10 and 12 formed of a ferromagnetic substance like ferrite and so forth. A coil groove 14 and a reinforcement groove 16 are provided in the magnetic core member 10, and the coil groove 14 is wound by a coil 18. Joint grooves 20 for restraining a track width are formed in the opposite sides of the pair of magnetic core members 10 and 12, and an adhesive glass 22 having a predetermined melting point fills the joint groove 20 and reinforcement groove 16. By means of the adhesive glass 22, the pair of magnetic core members 10 and 12 can be adhered to each other.
A stack layer 24 with a silicon dioxide SiO.sub.2 is formed on a contact plane including the track-width restraining joint groove 20 of the magnetic core member 12. As shown in FIG. 2, the stacking layer 24 is formed of layers, e.g., a first non-magnetic metal film 24a composed of chromium Cr, a ferromagnetic film 24b of a sendust which is an alloy of Fe--Al--Si(Sendust), a first non-magnetic film 24c of SiO.sub.2, a second non-magnetic metal film 24d of Cr and a second non-magnetic film 24e of SiO.sub.2, sequentially covering the surface of the magnetic core member 12.
Here, the first non-magnetic metal film 24a is utilized to improve the adhesive intensity between the magnetic ferrite core member 12 and sendust 24b, and the first non-magnetic film 24c of SiO.sub.2 and the second non-magnetic metal film 24d are used to form a magnetic gap.
Such a magnetic head is used for digital audio tape recorders, digital video tape recorders or 8 mm-video tape recorders. The pair of magnetic core members 10 and 12 are formed of a ferromagnetic substance such as Mn--Zn group monocrystalline ferrite, and the non-magnetic film of SiO.sub.2 is provided in the magnetic gap. A fabricating process of the conventional magnetic head shown in FIG. 1 will be described in detail with reference to FIGS. 3A to 3F.
FIGS. 3A to 3F illustrates the fabricating steps of the magnetic head shown in FIG. 1. As shown in FIG. 3A, a pair of magnetic core blocks 10a and 12a shaped as a predetermined rectangles by cutting the ferromagnetic substance such as ferrite. After at least one contact plane to be jointed, e.g., a plane of the magnetic core block 12a, is subjected to an abrasion process to be smoothed, the joint grooves 20 for restraining track width by a predetermined interval are provided along the lengthwise direction of the magnetic core blocks 10 and 12a. The magnetic core block 10a has the coil groove 14 and reinforcement groove 16 successively in its lengthwise direction.
As shown in FIG. 3B, on the magnetic core block 12a, the stacking layer 24 shown in FIG. 2 obtained by successively stacking the first non-magnetic metal film 24a, sendust layer 24b, first non-magnetic film 24c, second non-magnetic metal film 24d and second non-magnetic film 24e is formed via a proper method, e.g., the sputtering. Also, a glass 22a of SiO.sub.2 --PbO group is put on the track-width restraining joint groove 20, coil groove 14 and reinforcement groove 16 of the magnetic core block 10a.
The glass 22a is first heated to be melted, and then the glass 22a having a low melting point fills in the track-width restraining joint groove 20, coil groove 14 and reinforcement groove 16 as shown in FIG. 3C. As shown in FIG. 3D, the glass 22a having the low melting point filling in the coil groove 14 is ground to expose the lower portion of the coil groove 14. The glass 22a out of the track-width restraining joint groove 20, coil groove 14 and reinforcement groove 16 is removed via an abrasion, etc.
Then, the glass 22a having the low melting point is sputtered onto the joint plane of the magnetic core block 10a. As shown in FIG. 3E, the magnetic core blocks 10a and 12a face to be jointed to each other are secondly heated at the melting temperature of the glass 22a to allow the magnetic core blocks 10a and 12a to bond to each other by the glass 22a.
The completely-bonded magnetic core blocks 10a and 12a are cut along a cut line C as shown in FIG. 3E, and, at the same time, an unnecessary portion on the lower portion of the reinforcement groove 16 is cut along a cut line D, so that at least one half-finished magnetic head shown in FIG. 3F is obtained. A plane contacting a magnetic recording medium is abraded in a circular-arc shape, and the coil 18 is wound around the coil groove 14 to complete the magnetic head having the structure shown in FIG. 1.
However, in fabricating the conventional magnetic head, especially in bonding two magnetic core members to each other, the glass layer is molded or sputtered to the magnetic core members forming the magnetic head, so that a gap length control is difficult to be hard to adjust thickness variation of the glass layer. Also, due to the spreading property of the glass, a plurality of magnetic core members cannot be simultaneously handled to block the improvement of productivity. Moreover, since the adhesion process is generally carried at 400.degree. to 700.degree. C., the magnetic property of the material is apt to be degraded.
In other words, the adhesive glass must have a hardness and a spreading property capable of firmly bonding two magnetic ferrite members to each other without causing bubbles. However, the adhesive glass used for the magnetic head according to the conventional technique produces bubbles by the reaction to the stacking layer. The bubbles are confined within the glass to be holes and appear in the contact plane with the recording medium, thereby scratching the recording medium.